An accident involving a hotel shuttle bus has left at least 16 people, and as many as 18, injured outside Atlanta’s Hartsfield-Jackson International Airport, police said.

The Georgia Department of Transportation said the wreck happened on Loop Road near the exit from I-85 northbound.

“They’re currently working an accident involving a hotel shuttle bus on North Loop Road in front of the AirTran hangar,” Atlanta police Officer K.Y. Jones told CNN.

Nine people were being transported to Grady Memorial Hospital for treatment and nine were being taken to Atlanta Medical Center, Atlanta Fire Rescue Department spokeswoman Janet Ward told the AJC. The most serious injury was suffered by the shuttle driver, according to College Park police.

Grady Hospital reported just before noon that 10 patients had been transported there, and that two were considered to be in critical condition.

The shuttle bus reportedly slammed into the left side of a tractor-trailer that was making a U-turn. The truck driver was not injured, and police department officials said they had not yet been determined whether the U-turn was legal.

Georgia DOT reports that the ramp from I-85 northbound to Loop Road was shut down by the crash.

The bus was a shuttle for Hampton Inn, Fairfield Inn and Hilton hotels, and was operated by MTI Limos.